Question

I have a function:

 public static List<T> EntityCache<T>(this System.Linq.IQueryable<T> q, ObjectContext dc, string CacheId)
    {


        try
        {
            List<T> objCache = (List<T>)System.Web.HttpRuntime.Cache.Get(CacheId);

            string connStr = (dc.Connection as System.Data.EntityClient.EntityConnection).StoreConnection.ConnectionString;

            if (objCache == null)
            {
                ObjectQuery<T> productQuery = q as ObjectQuery<T>;

                string sqlCmd = productQuery.ToTraceString();

                using (System.Data.SqlClient.SqlConnection conn = new System.Data.SqlClient.SqlConnection(connStr))
                {
                    conn.Open();
                    using (System.Data.SqlClient.SqlCommand cmd = new System.Data.SqlClient.SqlCommand(sqlCmd, conn))
                    {

                        string NotificationTable = q.ElementType.Name;
                        System.Web.Caching.SqlCacheDependency sqldep = new System.Web.Caching.SqlCacheDependency(cmd);
                        cmd.ExecuteNonQuery();
                        objCache = q.ToList();
                        System.Web.HttpRuntime.Cache.Insert(CacheId, objCache, sqldep);
                    }
                }
            }

            return objCache;

        }
        catch (Exception ex)
        {
            throw ex;
        }

    }

q can be a table, view or a procedure.

What i want is to find the underlying tables associated with a view or a procedure.

like if q is a join of tow tables i want to get the name of both the tables and finally

execute like:

If there are tw0 tables say A and B

Then i need to make Aggregate Dependency like:

  string sqlCmd1 = string.Empty;
                        string sqlCmd2 = string.Empty;

                        using (testEntities ctx1 = new testEntities())
                        {
                            sqlCmd1 = ((System.Data.Objects.ObjectQuery)(from p in ctx1.A select p)).ToTraceString();
                            sqlCmd2 = ((System.Data.Objects.ObjectQuery)(from p in ctx1.B select p)).ToTraceString();
                        }

                        System.Data.SqlClient.SqlCommand cmd1 = new System.Data.SqlClient.SqlCommand(sqlCmd1, conn);
                        System.Data.SqlClient.SqlCommand cmd2 = new System.Data.SqlClient.SqlCommand(sqlCmd2, conn);


 System.Web.Caching.SqlCacheDependency
                       dep1 = new System.Web.Caching.SqlCacheDependency(cmd1),
                       dep2 = new System.Web.Caching.SqlCacheDependency(cmd2);

                        System.Web.Caching.AggregateCacheDependency aggDep = new System.Web.Caching.AggregateCacheDependency();
                        aggDep.Add(dep1, dep2);

                        cmd1.ExecuteNonQuery();
                        cmd2.ExecuteNonQuery();

then the query i want to execute is

select * from A;
select * from B;

This i am using for SqlCacheDependency using Linq to Entity.

It works well for views when i hardcode the underlying tables but now i want the code automatically check for the underlying tables

and execute nonquery like

   cmd1.ExecuteNonQuery();
   cmd2.ExecuteNonQuery();

and make aggregate dependencies.

Any help is appreciated.

Thanks.

Answer 1

You must use database level tools to find which database objects your views or stored procedures depends on (but it also means you must know their full names in the database). For example SQL server offers sp_depends system stored procedure to track dependencies. This can be quite complicated because dependencies can have multiple levels (procedure can be dependent on view, view can be dependent on another view, etc.).

Be aware that advanced EF mapping also allows writing SQL directly to EDMX and in such case you will have to parse ToTraceString to find database objects.